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The acceleration of soil erosion by water in most regions of the world in response to the anthropogenic modification of landscapes is a serious threat to natural ecosystem functionalities because of the loss of invaluable constituents such as soil particles and organic carbon (OC). While soil OC erosion is likely to be a major component of the global C cycle, water erosion-induced CO₂ emissions remain uncertain. In this study, our main objective was to compare the release of CO₂ from eroded topsoils and from the sediments exported by diffuse erosion during an entire rainy season. Conventional tillage (CT) and no-tillage (NT) maize treatments were considered in an attempt to set up best management practices to mitigate gaseous OC losses from agricultural soils. The study was conducted in the KwaZulu-Natal province in South Africa, whereas in many other areas of the developing world, erosion is severe and crop residue scarcity is the main challenge. CO₂ emissions from undisturbed 0–0.02m soil samples collected within 2.25m×10m runoff plots and from exported sediments by water erosion, were evaluated continuously at the laboratory over a 140-day period and compared to soil OC stocks. NT significantly reduced CO₂ emissions from both soils and sediments. Overall NT, which exhibited a greater carbon density than CT (17.70 vs 13.19kgCm⁻³), reduced soil gaseous emissions by 4.4% (10.40 vs 10.88gCO₂-Cm⁻², P
